Electric arc welding shielding gas flow control method and control system

Abstract

The invention relates to the field of additive manufacturing control, and discloses an electric arc welding shielding gas flow control method and control system.The electric arc welding shielding gas flow control method comprises the following steps that S10, the type of welding shielding gas is obtained; s20, protective gas is supplied at the set initial flow, and the welding machine is started for electric arc welding; s30, the average welding current in the set time period is obtained; s40, shielding gas flow control values corresponding to the welding process, the shielding gas types and the average welding current are obtained from the process database; and S50, controlling the flow of the shielding gas according to the flow control value. The electric arc welding shielding gas flow control system is used for achieving the electric arc welding shielding gas flow control method, it can be guaranteed that the flow of the shielding gas meets the actual requirement in the electric arc welding process, and meanwhile waste of the shielding gas is reduced.

Description

Technical Field

[0001] The present application relates to the field of additive manufacturing control, and more particularly to a method for controlling the flow rate of shielding gas for arc welding. Furthermore, the present application also relates to a flow rate control system for shielding gas for arc welding. Background Art

[0002] Additive manufacturing technology is a technique for manufacturing physical parts by gradually adding materials. Broadly speaking, additive manufacturing includes 3D printing, cladding processing, and welding processing. In the additive manufacturing process, it is usually necessary to form a molten pool on the base material using a laser and / or electric arc, melt the additive material in the molten pool, and form the corresponding physical structure after the molten pool solidifies. When the base material and the additive material are in a molten state and at high temperature, they are easily oxidized when in contact with oxygen in the air, and easily nitrided when in contact with nitrogen in the air, which affects the quality of welding. Therefore, in the additive manufacturing process, it is usually necessary to introduce a shielding gas into the additive area. The chemically inactive shielding gas is used to isolate the oxygen and nitrogen in the air to prevent oxidation and nitridation of the base material and the additive material.

[0003] During arc welding, the temperature and range of the molten pool formed by the arc are closely related to factors such as the arc welding process and welding current. The shielding gas flow rate required to isolate the air also varies. When using different shielding gases, such as CO2 and Ar, the required shielding gas flow rate also varies. This requires using different shielding gas flows when welding with different arc welding processes and at different stages of the welding process. This ensures effective isolation of the air, protection of the base material and additive materials, while minimizing shielding gas consumption.

[0004] Existing arc welding equipment typically requires manual adjustment of the throttle valve opening to adjust the shielding gas flow rate to the current welding conditions when the welding process or welding current changes. However, manual adjustment lacks precision and real-time control of the shielding gas flow rate, and it cannot rule out insufficient shielding gas flow due to human error, thus affecting welding quality. Manual adjustment often supplies shielding gas at the maximum flow rate required for a specific welding stage, resulting in waste of shielding gas. Summary of the Invention

[0005] In order to ensure that the flow rate of shielding gas meets the actual needs during arc welding and reduce the waste of shielding gas, the present application provides an arc welding shielding gas flow control method and control system.

[0006] The arc welding shielding gas flow control method provided in this application adopts the following technical solutions: A method for controlling the flow rate of shielding gas for arc welding comprises the following steps: S10, obtaining the type of welding shielding gas; S20, supplying shielding gas at a set initial flow rate, and starting a welder for arc welding; S30, obtaining an average welding current within a set time period; S40, obtaining a shielding gas flow rate control value corresponding to the welding process, the type of shielding gas, and the average welding current from a process database; and S50, controlling the shielding gas flow rate according to the flow rate control value.

[0007] By adopting the above technical solution, and utilizing the shielding gas flow control values corresponding to different welding processes, shielding gas types, and average welding currents stored in the process database, the shielding gas flow can be precisely controlled, ensuring that the shielding gas flow meets the needs of the welding process while reducing shielding gas waste. By controlling the shielding gas flow using the average welding current within a set time period, the shielding gas flow can be adapted to the weld pool temperature and weld pool range during welding, while reducing the need for significant adjustments to the shielding gas flow due to instantaneous changes in the welding current. This reduces the need for frequent and significant adjustments to the flow control valve used to control the shielding gas flow, ensuring the real-time and precision of shielding gas flow regulation and reducing shielding gas flow fluctuations.

[0008] In a specific possible implementation scheme, in S30, the real-time welding current of the welding machine is obtained by detecting the current in the welding cable using a Hall current sensor, and the average welding current is obtained by calculating the arithmetic mean of the absolute value of the welding current within a set time.

[0009] By adopting this technical solution, using a Hall effect current sensor to detect the current in the welding cable, the arc welder's welding current can be accurately obtained while isolating the detection signal from the welding current, minimizing the impact of welding current detection on the welding current. By using the arithmetic mean of the real-time welding current absolute value as the average welding current, the influence of the welding current direction on the average welding current value can be eliminated, thereby accurately determining the average welding current for AC and DC arc welding and ensuring that the average welding current is positively correlated with the temperature and range of the weld pool.

[0010] In a specific feasible implementation scheme, in S30, it also includes: obtaining the current flow rate of the shielding gas; in S50, adjusting the flow rate of the shielding gas using the PID control method according to the flow control value of the shielding gas and the current flow rate, so that the flow rate of the shielding gas reaches the flow control value.

[0011] By adopting the above technical solution, the required protective gas flow rate is obtained by using the flow control value and the current flow rate according to a certain PID adjustment, which can make the protective gas flow rate change smoothly toward the flow control value, making the valve port adjustment of the flow control valve smoother and preventing over-adjustment of the protective gas flow rate.

[0012] In a specific embodiment, obtaining the current flow rate of the shielding gas and adjusting the flow rate of the shielding gas are both performed through a gas flow control valve.

[0013] By adopting the above technical solution and utilizing a gas flow control valve that has both gas flow control function and gas flow collection function, it is possible to adjust the gas flow or the actual gas flow value at the same time, which is beneficial to improving the gas flow regulation accuracy and the smoothness of gas flow regulation.

[0014] In a specific feasible implementation scheme, in S40, the flow control value in the process database is obtained by theoretical calculation based on different welding processes and different types of shielding gases, selecting different welding current points, and verifying and adjusting the actual welding process under the corresponding welding current point; if the average welding current is equal to the welding current point in the process database, the flow control value corresponding to the welding current point is directly obtained from the process database; if the average welding current is between two welding current points in the process database, the linear proportional value of the flow control values corresponding to the two welding current points in the process database is used as the flow control value.

[0015] By adopting this technical solution and utilizing a process database derived from theoretical calculations and validated through actual welding processes, the accuracy of the process database data can be improved, significantly reducing shielding gas consumption while ensuring arc welding quality. Using a linear proportional value as the flow control value between two adjacent welding current points can reduce the size of the process CNC library and the workload of setting up and validating the process database, while ensuring shielding gas flow control accuracy at different average welding currents.

[0016] In a specific feasible implementation scheme, in S50, the user can input a flow fine-tuning value to fine-tune the shielding gas flow according to the welding quality of the welder, and store the flow fine-tuning value in the process database; the user can choose to control the shielding gas flow only according to the flow control value in the process database, or control the shielding gas flow according to the sum of the flow control value and the flow fine-tuning value in the process database.

[0017] By adopting the above technical solution, the corresponding flow control value in the process database is fine-tuned using the input flow fine-tuning value, which can make the shielding gas flow more consistent with the arc welding needs under current production conditions, ensuring that the shielding gas flow rate is more suitable for the needs of current production conditions. By allowing the user to select the shielding gas flow control method to use only the flow control value in the process database, the original shielding gas flow control standard can be quickly restored after the production conditions change, preventing the flow fine-tuning value in the process database from causing confusion in the shielding gas flow control standard, and reducing the workload of re-adjusting the flow fine-tuning value.

[0018] The arc welding shielding gas flow control system provided in this application adopts the following technical solutions: An arc welding shielding gas flow control system includes a gas flow control module, a welding current acquisition module, a lower controller and a host computer, the gas flow control module includes a DAC, a flow control valve, a flow sensor, a first differential amplifier unit and a first ADC, the DAC and the first ADC are connected to the lower controller, the flow control valve and the flow sensor are both arranged on the shielding gas output pipeline of the arc welding machine, the DAC is connected to the flow control valve, and the first differential amplifier unit is connected between the flow sensor and the first ADC; the welding current acquisition module includes a Hall current sensor, a second differential amplifier unit and a second ADC, the Hall current sensor is arranged on the welding cable of the arc welding machine and is connected to the second differential amplifier unit, the second ADC is connected between the second differential amplifier unit and the lower controller, and the lower controller is connected to the host computer, so as to implement the arc welding shielding gas flow control method of the present application.

[0019] By adopting the above technical solution and utilizing a differential amplifier and ADC (analog-to-digital converter) connected between the sensor and the lower-level controller, it is possible to precisely match the sensor detection signal with the lower-level controller input signal, improving the stability and accuracy of the sensor detection signal and ensuring the control accuracy of the shielding gas flow. By simultaneously installing a flow control valve and a flow sensor on the shielding gas output pipeline of the arc welding machine, the actual shielding gas flow rate detected by the flow sensor can be used to feedback adjust the flow control valve, thereby improving the flow control accuracy of the flow control valve.

[0020] In a specific embodiment, the flow sensor is integrated into the flow control valve.

[0021] By adopting the above technical solution, a flow control valve with both flow control and flow collection functions is formed by integrating a flow sensor on the flow control valve. This can collect the actual flow rate of the protective gas while adjusting the flow rate of the protective gas, reduce the fluctuation of the protective gas flow rate during the adjustment process, and improve the smoothness and adjustment accuracy of the protective gas flow adjustment.

[0022] In a specific implementation scheme, the first differential amplifier unit and the second differential amplifier unit both include a differential amplifier circuit and a voltage follower, the differential amplifier circuit is connected to the flow sensor or the Hall current sensor, and the voltage follower is arranged between the differential amplifier circuit and the lower controller.

[0023] By adopting the above technical solution, the differential amplifier circuit can highly amplify the sensor detection signal while improving the linearity of the amplified signal, suppressing common-mode signals, and ensuring the accuracy of the sensor detection signal. The voltage follower circuit can ensure that the sensor detection signal meets the input requirements of the ADC, reduce the output impedance of the detection signal, and reduce the impact of the ADC circuit on the sensor detection signal, thereby improving the accuracy of the shielding gas flow rate and welding current acquisition.

[0024] In a specific feasible implementation scheme, the lower controller includes an average value filter module, a Kalman filter module and a PID control module. The average value filter module is connected to the second ADC so as to obtain the arithmetic mean of the absolute value of the welding current transmitted by the second ADC within a set time; the Kalman filter module is connected to the second ADC so as to predict the changing trend of the welding current and the adjustment amount of the protective gas flow; the PID control module is connected to the first ADC and the host computer so as to control the flow rate of the flow control valve according to the flow control value and the current flow.

[0025] By adopting the above technical solution, the average value filtering module can be used to quickly obtain the average welding current within the set time, reducing the calculation amount and calculation time of the average welding current; the Kalman filtering module can be used to predict the changing trend of the welding current, thereby predicting the changing trend of the average welding current and the adjustment direction of the protective gas flow, avoiding large-scale reverse adjustment of the flow control valve, and improving the smoothness and adjustment accuracy of the flow control valve adjustment.

[0026] In summary, this application includes at least one of the following beneficial technical effects: 1. By obtaining the average welding current of the welding machine within the set time and controlling the shielding gas flow rate according to the average welding current, the shielding gas supply can be adapted to the welding pool temperature and weld pool range caused by the average welding current. While ensuring the shielding gas's air isolation effect, it reduces shielding gas consumption, saves shielding gas, and reduces the large and frequent adjustments to the shielding gas flow rate due to instantaneous changes in the welding current, making the adjustment of the shielding gas flow rate smoother.

[0027] 2. By setting up a process database of shielding gas flow control values corresponding to different welding processes, different types of shielding gases, and different average welding currents, the flow control value of the shielding gas under the corresponding welding conditions can be quickly obtained, so that the supply of shielding gas can be controlled according to the flow control value, so that the shielding gas supply is adapted to the current welding conditions, while using the shielding gas to isolate and protect the welding area, reducing the consumption of shielding gas.

[0028] 3. The real-time welding current during the welding process is obtained by the Hall current sensor, and the average welding current is obtained by calculating the arithmetic mean of the absolute value of the welding current within the set time. This can reduce the impact of the welding current size collection on the welding current and ensure that the size of the obtained average welding current corresponds to the heat generation of the arc welding, so that the shielding gas supply is adapted to the heat generation of the arc welding.

[0029] 4. By using a flow control valve that has both flow control and flow acquisition functions, the actual flow value of the shielding gas can be obtained while adjusting the shielding gas flow, and the actual flow value of the shielding gas can be used to perform feedback adjustment on the flow control valve, which greatly improves the flow control accuracy of the flow control valve. In conjunction with the differential amplifier unit and ADC set between the sensor and the lower controller, the acquisition accuracy and control accuracy of the shielding gas flow are effectively improved. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] Figure 1 This is a flowchart of an embodiment of the arc welding shielding gas flow control method of the present application.

[0031] Figure 2 This is a partial structural diagram of a process database in one embodiment of the arc welding shielding gas flow control method of the present application.

[0032] Figure 3 This is a schematic diagram of obtaining flow control values under different welding currents from a process database in one embodiment of the arc welding shielding gas flow control method of the present application.

[0033] Figure 4 This is a structural principle diagram of an embodiment of the arc welding shielding gas flow control system of the present application.

[0034] Figure 5 This is a partial circuit schematic diagram of a Hall current sensor in one embodiment of the arc welding shielding gas flow control system of the present application.

[0035] Figure 6 This is a circuit schematic diagram of a differential amplifier unit in one embodiment of the arc welding shielding gas flow control system of the present application.

[0036] Explanation of the accompanying symbols: 1. Gas flow control module; 11. DAC; 12. Flow control valve; 13. Flow sensor; 14. First differential amplifier unit; 141. Differential amplifier circuit; 142. Voltage follower; 15. First ADC; 2. Welding current acquisition module; 21. Hall current sensor; 22. Second differential amplifier unit; 23. Second ADC; 3. Lower controller; 31. Average value filter module; 32. Kalman filter module; 33. PID control module; 4. Upper computer; 5. Arc welding machine. DETAILED DESCRIPTION

[0037] The specific embodiments of the present application are described in detail below with reference to the accompanying drawings. It should be understood that the specific embodiments described herein are only used to illustrate and explain the present application and are not intended to limit the present application.

[0038] The terms "first" and "second" are used for descriptive purposes only and should not be understood as indicating or implying relative importance or implicitly indicating the number of technical features indicated. Therefore, the features defined as "first" and "second" may explicitly or implicitly include one or more of the said features.

[0039] In the description of this application, it should be noted that, unless otherwise expressly specified or limited, the terms "disposed" and "connected" should be understood in a broad sense. For example, they can refer to fixed connections, detachable connections, or integral connections; they can refer to direct connections or indirect connections through an intermediate medium; they can refer to internal communication between two components or the interaction between two components. Those skilled in the art will understand the specific meanings of the above terms in this application based on the specific circumstances.

[0040] An embodiment of the arc welding shielding gas flow control method of the present application is as follows: Figure 1 As shown, the following steps are included: S10. Obtain the type of welding shielding gas.

[0041] When performing arc welding, the arc is used to heat the base material of the workpiece in the welding area and the additive material used in the welding process, so that the base material and additive material in the welding area melt and mix together to form a molten pool. This makes the temperature of the welding area very high. If the base material and additive material in a high-temperature state come into contact with air, they will react with the oxygen in the air to produce harmful oxides, and react with the nitrogen in the air to produce harmful nitrides, resulting in poor material quality in the welding area and affecting the strength of the welding area. Therefore, it is necessary to introduce a shielding gas into the welding area to isolate the air with the shielding gas, prevent the high-temperature base material and additive material from coming into contact with the air, and thus improve the quality of the welding.

[0042] The type of shielding gas can be manually input by the operator, such as manually selecting or inputting it into an automatic control system. Alternatively, a specific sensor can be installed on the shielding gas input pipeline to detect the type of shielding gas. Common shielding gases include CO2 and Ar. When arc welding products made of different materials, different types of shielding gases can be selected. When using different gases as shielding gases, the flow rate requirements of the shielding gas are also different. After determining the type of welding shielding gas, different flow control schemes are usually adopted for different shielding gases.

[0043] S20: Supply shielding gas at a set initial flow rate and start the welding machine to perform arc welding.

[0044] Before welding begins, shielding gas is usually supplied at a small initial flow rate so that the welding area is covered in shielding gas and isolated from oxygen and nitrogen in the air. Arc welding is then started to ensure that the base material and additive material in the welding area are heated and melted to form a molten pool while being isolated from air, preventing oxidation or nitridation of the material at high temperatures.

[0045] S30: Obtain the average welding current within a set time period.

[0046] The amount of heat generated during welding is positively correlated with the welding current: the magnitude of the welding current determines the strength of the arc, and the result of the arc action is heat. The accumulation of heat in the welding area causes the temperature of the welding area to rise. The temperature of the welding area usually depends on the accumulation of heat over a period of time, and the temperature of the welding area is usually more closely related to the average welding current over a period of time. This application uses the average welding current within a set time period, such as 1 second, as an indicator to judge the temperature of the welding area, so as to control the flow rate of the shielding gas. On the one hand, the welding current is the reason for the temperature increase in the welding area, and it has a certain degree of advance compared to directly measuring the temperature of the welding area; on the other hand, the use of the average welding current can avoid the instantaneous fluctuation of the welding current that leads to excessive adjustment of the shielding gas flow rate, which can make the adjustment of the shielding gas flow rate smoother.

[0047] S40. Obtaining a shielding gas flow control value corresponding to the welding process, shielding gas type, and average welding current from a process database.

[0048] The rate at which heat is generated in the weld zone depends not only on the welding current but also on the welding process. Different welding processes, such as plasma arc welding, tungsten inert gas arc welding, or metal arc welding, produce different amounts of heat.

[0049] The temperature of the welding area is not only related to the heat generation rate, but also to the heat dissipation rate. The heat dissipation is affected by many factors, and the influencing factors are relatively complex. As a result, there is no definite functional relationship between the temperature of the welding area and the average welding current within a set time period. Usually, it cannot be quickly calculated through several influencing factors.

[0050] By establishing a process database that shows the correspondence between shielding gas flow and welding process, shielding gas type and average welding current, it is possible to form a definite correspondence between shielding gas flow and average welding current when using different welding processes and different shielding gases, so that the average welding machine current can be used to form fast and real-time control of shielding gas flow.

[0051] S50: Control the flow rate of the shielding gas according to the flow control value.

[0052] The shielding gas flow is controlled according to the flow control value corresponding to the average welding current extracted from the process database, so that the real-time flow of the shielding gas is adapted to the current average welding current. This can ensure that the shielding gas effectively covers the welding area with higher temperature, thereby forming an effective isolation between the welding area and the air; at the same time, it can prevent the shielding gas flow introduced into the welding area from being too high, resulting in excessive consumption of shielding gas and waste of shielding gas.

[0053] The arc welding shielding gas flow control method of the present application can be implemented using the arc welding shielding gas flow control system of the present application.

[0054] In some embodiments of the arc welding shielding gas flow control method of the present application, in step S30, the real-time welding current of the welder is detected by providing a Hall effect current sensor on the welding cable connecting the welder to the welding gun. Using a Hall effect current sensor to detect the welding current passing through the welding cable avoids the need for connecting a mutual inductance element to the welding cable, eliminates the need for any modification to the welding cable feeder, reduces the impact of the detection circuit on the welding cable and welding current, and improves the safety of the detection circuit.

[0055] Welding current can be either direct current or alternating current, and the arc's heat production is directly related to the magnitude of the welding current, not its direction. When calculating the average welding current over a set time, it's important to ignore the current's direction and calculate the arithmetic mean of its absolute value. This average current provides a better correlation with the arc's heat production.

[0056] In a preferred embodiment of the arc welding shielding gas flow control method of the present application, in step S30, the current shielding gas flow rate is also obtained. The current shielding gas flow rate can be obtained by providing a flow sensor on the shielding gas delivery pipeline, or by feedback from a flow control valve that controls the shielding gas flow rate. The obtained current shielding gas flow rate can also be used to perform feedback adjustment on the flow control valve, thereby improving the flow control accuracy of the flow control valve.

[0057] In step S50, when the flow control valve is used to adjust and control the flow of protective gas, the valve opening of the flow control valve is adjusted by the PID control method according to the flow control value of the protective gas and the current flow value obtained, so that the valve opening of the flow control valve can change smoothly, thereby making the protective gas flow through the flow control valve smoothly approach the flow control value and finally reach the flow control value.

[0058] PID control, also known as proportional-integral-derivative control, has a simple algorithm, good robustness, and high reliability, which enables the shielding gas flow regulation process to have both excellent responsiveness and good flow regulation stability.

[0059] As a specific embodiment of the arc welding shielding gas flow control method of the present application, a gas flow control valve having both gas flow control and gas flow acquisition functions is provided on the shielding gas delivery pipeline, such as the PFCA750 air flow controller from SMC Automation Co., Ltd. This allows the shielding gas flow to be adjusted while also being able to obtain the current flow rate of the shielding gas.

[0060] In some embodiments of the arc welding shielding gas flow control method of the present application, the process database used in step S40, the flow control value in the database is selected according to a set number of welding current points according to a certain rule based on different welding processes and under different shielding gas types, and the theoretical calculation value is obtained through theoretical calculation based on the influence of different factors. Then, the welding current of the welding machine is adjusted to each welding current point, and the shielding gas flow is set to the corresponding theoretical calculation value for actual arc welding. During the welding process, the theoretical calculation value is verified and adjusted according to the welding quality to obtain the corresponding flow control value in the process database.

[0061] like Figure 2 and Figure 3 As shown, if, during the actual welding process, the average welding current calculated based on the real-time welding current collected over a certain period of time is exactly equal to a welding current point in the process database, the flow control value corresponding to that welding current point is directly extracted from the process database. If the average welding current calculated based on the real-time welding current is between the two closest welding current points in the process database, the flow control values corresponding to the two welding current points in the process database are extracted separately. Based on the position of the average welding current between the two welding current points, a linear ratio of the two corresponding flow control values is calculated, and this linear ratio is used as the corresponding flow control value.

[0062] This method can achieve the same control accuracy as a larger database by using a relatively small number of welding current points to form a relatively small database. By reducing the number of welding current points to select, the workload of establishing and verifying the process database is greatly reduced. Compared to the method of using the flow control value corresponding to the closest welding current point, this method has higher control accuracy.

[0063] In a preferred embodiment of the arc welding shielding gas flow control method of the present application, as Figure 2 As shown, during the arc welding process, in step S50, the shielding gas flow rate is controlled according to the flow control value extracted from the process database. The user can input the flow fine-tuning value in the control system at any time according to the welding quality of the welder to fine-tune the shielding gas flow rate under different welding conditions during the welding process.

[0064] For example, when welding at an average welding current of 300A, the system extracts a flow control value of 15 from the process database, controlling the flow control valve to output a shielding gas flow rate of 15 L / min. However, when observing the actual weld, field staff discover that the shielding gas is not providing adequate protection. In this case, they can input a flow adjustment value of 0.05 into the control system. The control system then superimposes the flow adjustment value with the flow control value and controls the flow control valve based on this superimposed flow control value of 15.05, generating a shielding gas flow rate of 15.05 L / min for optimal protection.

[0065] Similarly, when on-site staff judge that the shielding gas flow is too large by observing the actual welding effect of the weld, they can enter a negative flow fine-tuning value in the control system. The control system will use the flow fine-tuning value to negatively adjust the flow control value, reducing the inlet flow of shielding gas and reducing the waste of shielding gas.

[0066] Usually the adjustment accuracy of the flow fine-tuning value is two decimal places, and the flow control value after adjustment by the flow fine-tuning value cannot exceed the allowable control range of the flow control valve.

[0067] After the user enters any flow fine-tuning value, the system stores it in the process database at the location corresponding to the current welding current point. If the current average welding current corresponds to a point between the two closest welding current points, the system automatically linearly distributes the flow fine-tuning value and stores it in the locations corresponding to the two closest welding current points. When the system calls the flow control value in the process database, it automatically adjusts the flow fine-tuning value to the corresponding flow control value and uses the adjusted flow control value to control the shielding gas flow so that the shielding gas flow meets the requirements of the current actual welding conditions.

[0068] Each time the system is restarted, the system will prompt the user to choose whether to control the shielding gas flow based solely on the flow control values in the process CNC library, or based on the sum of the flow control values and the flow fine-tuning values in the process database, thereby meeting the needs of changing welding conditions, such as whether to change the batch of welded product materials. If the user chooses to control the shielding gas flow based solely on the flow control values in the process CNC library, the system will ask the user to confirm whether to adjust the flow control value when the user first enters the flow fine-tuning value. Once the user confirms, the system automatically clears all previously stored flow fine-tuning values in the process database for the same welding process and the same shielding gas type.

[0069] An embodiment of the arc welding shielding gas flow control system of the present application is as follows: Figure 4 As shown, the system includes a gas flow control module 1, a welding current acquisition module 2, a lower-level controller 3, and a host computer 4. The gas flow control module 1 includes a DAC 11, a flow control valve 12, a flow sensor 13, a first differential amplifier 14, and a first ADC 15. The DAC 11 uses a 12-bit high-precision DAC (digital-to-analog converter), and the first ADC 15 uses a high-precision ADC 16. The DAC 11 and the first ADC 15 are each connected to the lower-level controller 3.

[0070] The lower controller 3 is usually a control chip with lower computing power. The lower controller 3 can receive the shielding gas flow signal detected by the flow sensor 13 and the welding current signal obtained by the welding current acquisition module 2, and send a control signal to control the action of the flow control valve 12, thereby improving the real-time control of the flow control valve 12.

[0071] Shielding gas is delivered from a shielding gas source, such as a gas tank storing shielding gas, to the welding gun of the arc welder 5 or a location near the welding gun through a shielding gas output pipeline, so that the shielding gas flows toward the welding area of the welding gun. A gas source solenoid valve is also provided on the shielding gas output pipeline adjacent to the shielding gas source. The gas source solenoid valve is connected to the arc welder 5. After the arc welder 5 is turned on, the arc welder 5 sends a control signal to control the gas source solenoid valve to open. A flow control valve 12 is provided on the shielding gas output pipeline of the arc welder 5. A DAC 11 is connected between the flow control valve 12 and the lower controller 3. It can convert a digital control signal related to the flow control value sent by the lower controller 3 into an analog signal to control the operation of the flow control valve 12, driving the flow control valve 12 to adjust the valve opening so that the flow of shielding gas passing through the flow control valve 12 is equal to the flow control value.

[0072] A flow sensor 13 is installed on the shielding gas output pipeline of the arc welder 5 to detect the shielding gas flow rate passing through the shielding gas output pipeline. A first differential amplifier unit 14 is connected to the flow sensor 13 and is capable of amplifying the flow detection signal generated by the flow sensor 13 to ensure the stability and output capacity of the flow detection signal. A first ADC 15 is connected between the first differential amplifier unit 14 and the lower-level controller 3 and is capable of converting the flow detection signal amplified by the first differential amplifier unit 14 into a digital signal compatible with the lower-level controller 3, which is then transmitted to the lower-level controller 3 for processing.

[0073] The lower controller 3 can also perform feedback adjustment on the flow control valve 12 according to the actual flow of the protective gas detected by the flow sensor 13, ensuring that the control result of the flow control valve 12 is consistent with the actual flow of the protective gas, thereby greatly improving the control accuracy of the flow control valve 12, so that the control accuracy of the flow control valve 12 can reach 0.001L / min.

[0074] The welding current acquisition module 2 includes a Hall current sensor 21, a second differential amplifier unit 22, and a second ADC 23. The Hall current sensor 21 can use the T60404-N4644-X052 current sensor module produced by LEM. The circuit schematic diagram of the current sensor module is shown in FIG. Figure 5 As shown in the figure, a Hall current sensor 21 is installed on the welding cable connecting the arc welder 5 to the welding gun. The ground wire of the welding cable passes through the Hall current sensor 21, allowing the Hall current sensor 21 to detect the welding current signal flowing through the welding cable. A second differential amplifier unit 22 is installed between the Hall current sensor 21 and the second ADC 23. It amplifies the welding current signal detected by the Hall current sensor 21 and transmits it to the second ADC 23.

[0075] The second ADC 23 uses 16 as a high-precision ADC and is connected to the lower controller 3. It can convert the welding current signal amplified by the second differential amplifier unit 22 into a digital signal compatible with the lower controller 3 and transmit it to the lower controller 3 for processing.

[0076] The host computer 4 can use an industrial computer or PC with greater data processing capabilities, or a cloud server. The host computer 4 is connected to the lower controller 3 and can receive data transmitted by the lower controller 3 to assist the lower controller 3 in performing data processing with high computing power. Usually, a process database is stored in the host computer 4. The lower controller 3 transmits information such as the arc welding process and the type of shielding gas input by the user to the host computer 4, and the host computer 4 screens the process database based on the relevant information. During the welding process, the lower controller 3 transmits the real-time welding current detected by the Hall current sensor 21, or the average current within a set time, to the host computer 4. The host computer 4 retrieves the corresponding flow control value from the process database and transmits the flow control value to the lower controller 3. After processing by the lower controller 3, a control signal is sent to the flow control valve 12 to control the flow of shielding gas passing through the flow control valve 12.

[0077] The arc welding shielding gas flow control system of the present application can be used to implement the arc welding shielding gas flow control method of any embodiment of the present application.

[0078] In a preferred embodiment of the arc welding shielding gas flow control system of the present application, a flow sensor 13 is integrated into the flow control valve 12, forming a flow control valve that simultaneously performs gas flow control and gas flow acquisition functions, thereby significantly improving the control accuracy and feedback precision of the flow control valve. The flow control valve 12 may also be integrated with an alarm function. If the gas flow detected by the flow sensor 13 does not reach the set gas flow rate for a period of time, the flow control valve outputs an alarm signal, prompting the user to take action.

[0079] In some embodiments of the arc welding shielding gas flow control system of the present application, the circuit schematic diagram of the first differential amplifying unit 14 and the second differential amplifying unit 22 is as follows: Figure 6 As shown. The first differential amplifier unit 14 and the second differential amplifier unit 22 both include a differential amplifier circuit 141 and a voltage follower 142. The differential amplifier circuit 141 and the voltage follower 142 can be integrated into the same integrated circuit chip, or can be implemented using different integrated circuits. The detection signal detected by the flow sensor 13 or the Hall current sensor 21 can be amplified by the differential amplifier circuit 141 to improve the driving capability of the detection signal. At the same time, the differential amplifier circuit 141 has a higher input impedance and can eliminate the common mode voltage, thereby ensuring the linearity of the amplified detection signal, increasing the anti-interference capability of the input signal, and reducing the influence of the amplifier circuit and the signal acquisition circuit, thereby ensuring the stability and reliability of the detection signal.

[0080] The voltage follower 142 is provided between the differential amplifier circuit 141 and the lower controller 3 , and can increase the null interference capability of the output detection signal and increase the load capacity of the detection signal, thereby ensuring that the output detection signal meets the input level requirement of the ADC.

[0081] In some embodiments of the arc welding shielding gas flow control system of the present application, as Figure 4 As shown, the lower controller 3 integrates a hardware average filter module 31, a Kalman filter module 32, and a PID control module 33. The average filter module 31 is connected to the second ADC 23 and automatically generates the arithmetic mean of the absolute value of the welding current based on the real-time welding current detection signal transmitted by the second ADC 23 within a set time period, thereby obtaining the average welding current for the set time period before the current moment. This reduces the computing power consumption of the lower controller 3 and improves the real-time performance of obtaining the smoothed welding current.

[0082] The Kalman filter module 32 is connected to the second ADC23, and can predict the changing trend of the welding current based on the real-time welding current detection signal transmitted by the second ADC23 within the set time, so that the shielding gas flow rate can be adjusted in time according to the prediction result, making the change of the shielding gas flow rate smoother, reducing the jitter of the shielding gas flow rate during the adjustment process, improving the real-time performance of the shielding gas flow rate adjustment, and the actual protection effect of the shielding gas.

[0083] The PID control module 33 is connected to the first ADC15 and the host computer 4. It can produce a control signal for adjusting the flow control valve 12 through the PID algorithm based on the flow control value retrieved by the host computer 4 from the process database and the current flow of the protective gas detected by the flow sensor 13, and control the valve opening of the flow control valve 12 so that the flow of protective gas passing through the flow control valve 12 approaches the flow control value in a set manner, making the control process of the protective gas flow smoother.

[0084] Throughout the description of this application, reference to terms such as "one embodiment," "specific embodiment," and "preferred embodiment" means that the specific features, structures, materials, or characteristics described in conjunction with that embodiment or example are included in at least one embodiment or example of this application. In this application, schematic representations of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in any one or more embodiments or examples.

[0085] The above are all preferred embodiments of the present application, and are not intended to limit the scope of protection of the present application. Therefore, any equivalent changes made based on the structure, shape, and principle of the present application should be included in the scope of protection of the present application.

Claims

1. A method for controlling the flow rate of shielding gas for arc welding, characterized in that: The steps include: S10, obtaining the type of welding shielding gas; S20, supplying shielding gas at a set initial flow rate, starting the welder to perform arc welding; S30, obtaining the average welding current within a set time period; S40, obtaining a shielding gas flow control value corresponding to the welding process, shielding gas type, and average welding current from a process database; S50: Control the flow rate of the shielding gas according to the flow control value.

2. The arc welding shielding gas flow control method according to claim 1, characterized in that: In S30, the real-time welding current of the welding machine is obtained by detecting the current in the welding cable using a Hall current sensor, and the average welding current is obtained by calculating the arithmetic mean of the absolute values of the welding current within a set time.

3. The arc welding shielding gas flow control method according to claim 2, characterized in that: In S30, it also includes: obtaining the current flow of the shielding gas; in S50, according to the flow control value of the shielding gas and the current flow, adjusting the flow of the shielding gas by using the PID control method so that the flow of the shielding gas reaches the flow control value.

4. The arc welding shielding gas flow control method according to claim 3, characterized in that: The current flow rate of the shielding gas is obtained and the flow rate of the shielding gas is adjusted through the gas flow control valve.

5. The arc welding shielding gas flow control method according to claim 1, characterized in that: In S40, the flow control value in the process database is obtained by theoretical calculation based on different welding current points selected according to different welding processes and different types of shielding gases, and is verified and adjusted through actual welding processes under the corresponding welding current points; if the average welding current is equal to the welding current point in the process database, the flow control value corresponding to the welding current point is directly obtained from the process database; if the average welding current is between two welding current points in the process database, the linear proportional value of the flow control values corresponding to the two welding current points in the process database is used as the flow control value.

6. The arc welding shielding gas flow control method according to claim 5, characterized in that: In S50, the user can input a flow fine-tuning value according to the welding quality of the welding machine to fine-tune the shielding gas flow, and store the flow fine-tuning value in the process database; The user can choose to control the shielding gas flow rate based only on the flow control value in the process NC library, or to control the shielding gas flow rate based on the sum of the flow control value and the flow fine-tuning value in the process database.

7. An arc welding shielding gas flow control system, characterized in that: The invention comprises a gas flow control module (1), a welding current acquisition module (2), a lower controller (3) and an upper computer (4), wherein the gas flow control module (1) comprises a DAC (11), a flow control valve (12), a flow sensor (13), a first differential amplifier unit (14) and a first ADC (15), wherein the DAC (11) and the first ADC (15) are connected to the lower controller (3), the flow control valve (12) and the flow sensor (13) are both arranged on the shielding gas output pipeline of the arc welding machine (5), the DAC (11) is connected to the flow control valve (12), and the first differential amplifier unit (14) is connected to the lower controller (3). between the flow sensor (13) and the first ADC (15); the welding current acquisition module (2) includes a Hall current sensor (21), a second differential amplification unit (22) and a second ADC (23), the Hall current sensor (21) is arranged on the welding cable of the arc welding machine (5) and is connected to the second differential amplification unit (22), the second ADC (23) is connected between the second differential amplification unit (22) and the lower controller (3), the lower controller (3) is connected to the upper computer (4), and the arc welding shielding gas flow control method according to any one of claims 1 to 5 can be implemented.

8. The arc welding shielding gas flow control system according to claim 7, characterized in that: The flow sensor (13) is integrated into the flow control valve (12).

9. The arc welding shielding gas flow control system according to claim 7, characterized in that: The first differential amplification unit (14) and the second differential amplification unit (22) both include a differential amplification circuit (141) and a voltage follower (142), wherein the differential amplification circuit (141) is connected to the flow sensor (13) or the Hall current sensor (21), and the voltage follower (142) is arranged between the differential amplification circuit (141) and the lower controller (3).

10. The arc welding shielding gas flow control system according to any one of claims 7 to 9, characterized in that: The lower controller (3) includes an average value filter module (31), a Kalman filter module (32) and a PID control module (33). The average value filter module (31) is connected to the second ADC (23) so as to obtain the arithmetic average value of the absolute value of the welding current transmitted by the second ADC (23) within a set time; the Kalman filter module (32) is connected to the second ADC (23) so as to predict the change trend of the welding current and the adjustment amount of the protective gas flow; the PID control module (33) is connected to the first ADC (15) and the upper computer (4) so as to control the flow rate of the flow control valve (12) according to the flow control value and the current flow rate.

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